Sound

Question 1

Def a longitudinal wave

Answer 1

Is a disturbance - the displacement of which is in the direction of propagation

Question 2

Define a wavelength

Answer 2

Is the distance between 2 corresponding points on two successive waves

Question 3

Define frequency

Answer 3

It is the number of waves passing a given point in one second

Question 4

Define Amplitude

Answer 4

It is the maximum displacement attained from the undisturbed position

Question 5

What is the formula for the speed of sound

Answer 5

V=d/t

v = velocity in m/s
d = distance travelled in m
t = time in s

Also v = lambda x f

Question 6

Describe an experiment to determinethe speed of sound

Answer 6

Tapemeasure
Stopwatch
Starters pistol

500m open field
3 pupils with stopwatches on one side
Another pupil 500m away firing the pistol
Stopwatches started when smokeis seen and stopped when sound is heard
Average of 3 times calculated
Use formula to calculate v=d/t

Question 7

Name 4 facts about sound

Answer 7

Travels faster at higher temperatures

Travels faster and better in liquids than air

Solids transmit sound best, fastet, and furthest

Greter speed in liquid and solids due to greater elasticity

Question 8

Define an echo

Answer 8

It is a repetition/s of sound caused by the reflection of soundwaves from a hard surface such as a wall or cliff

Question 9

Name 3 conditions necessary to form an echo

Answer 9

Loud enough sound

Large enough reflective surface (rock / wall)

Far enough from reflective surface (17m)

Question 10

Name 3 characteristics of sound

Answer 10

Pitch

Loudness

Quality

Question 11

What attribute of a wave cause the pitch of sound

Answer 11

Frequency

Question 12

Name 3 factors that determine the pitch of a piano string

Answer 12

Length

Thickness

Tension

Question 13

What attribute of a wave cause loudness

Answer 13

Amplitude

Question 14

What cause the quality of a note

Answer 14

Faint overtones formed along with the fundamental note

Question 15

What is meant by the quality of a note

Answer 15

It determines the difference in sound between a note played on a piano and the same note played on a violin

Question 16

What are the limits that the human ear is capable of hearing

Answer 16

20Hz - 20000Hz

Question 17

At what frequency do we describe ultrasound

Answer 17

20 000Hz and higher

Question 18

Give 4 uses of ultrasound

Answer 18

Image the human body -diagnostic tool

Industrially to find flaws in material and measure thickness of objects

As a non invasive sensor to detect the content of containers

To break up kidney stones without surgery

Question 19

Difference between a misical note and noise

Answer 19

Noise is caused by irregular vibration while a musical note is caused by a regular vibration

Question 20

Def electromagnetic waves

Answer 20

Are progressive transverse waves that are made up of alternating electric and magnetic fields that are at right angles to each other

Question 21

In what respect are all electromagnetic waves the same

Answer 21

They all travel at the same speed. 3 x 10 ^8m/s

Question 22

Electromagnetic waves differ from each other in respect to ……… And …….

Answer 22

Frequency

Wavelength

Question 23

Give 6 properties of EM waves

Answer 23

Can travel through a vacuum

Are transverse waves

Travel at a speed of 3 x 10^8 m/s in a vacuum

Exhibit reflection, refraction, diffeaction, interference and polarization

Transmit energy from one place to another

Can be absorbed by matter to cause heating and other effects

Question 24

How are radio waves produced?

Answer 24

By oscillating currents in an aerial

Question 25

A radio receiver does not need to be in line of sight from the transmitter to receive the signal - explain

Answer 25

Radiowaves can be diffracted or reflected around obstacles Long wave transmission is ised in mountainous areas because long waves are diffracted better over the mountain tops - so that transmissions can be received in the valleys. They are also reflected by charged particles in the ionosphere which makes long distance world service radio reception possible aroun the curvature of the earth

Question 26

Microwaves are at the Short /Long wavelength end of the radio band

Answer 26

Short

Question 27

Microwaves are used for

Answer 27

Cooking in microwave ovens For communication by cell phone and with satellites

Question 28

Infrared radiation is characterized by

Answer 28

Heat

Question 29

Infrared can be detected by

Answer 29

Skin Thermometer Temperature sensitive photographic film

Question 30

What is infrared radiation used for

Answer 30

Trigger burglar alarms In remote controlls for TVs In heaters toastera and grills To transmit communication signals in optical fibre cables

Question 31

White light can be split in all the component colours / spectrum of light Name the colours in decending wavelength

Answer 31

``` Red Orange Yellow Green Blue Indigo Violet ```

Question 32

Def monochromatic light

Answer 32

Light of one colour and therefore of one frequency

Question 33

Ultraviolet rays causes

Answer 33

Sunburn

Question 34

Name uses for ultraviolet radiation

Answer 34

Sunbed Security pens Fluorescent lights Killing virusses and bacteria

Question 35

How are x rays produced

Answer 35

In an x ray tube when high velocity electrons strike a metal target

Question 36

How are gamma rays produced

Answer 36

Radioactive decay of unstable atoms

Question 37

How can we detect gamma rays

Answer 37

Geiger counter

Question 38

What is gamma radiation used for

Answer 38

Sterilize surgical instruments To kill harmful bacteria in food To kill cancer cells

Question 39

List electromagnetic waves from longest to shortest wavelength

Answer 39

Radio waves Micro waves Infra red waves Visible waves Ultraviolet X rays Gamma rays

Question 40

Def sound waves

Answer 40

Are longitudinal waves that are Made up of a series of compressions and rarefactions caused by vibrations